1. Field of the Invention
The present invention relates, in general, to coffee bean roasters and methods for roasting coffee beans using the same and, more particularly, to a coffee bean roaster and a method for roasting coffee beans using the same in which green coffee beans are roasted by far-infrared radiant heat emitted from a ceramic heating plate while combustion gases generated from the roasting of the coffee beans are reburnt by a burner.
2. Description of the Related Art
Generally, a conventional method for producing coffee from green coffee beans comprises: roasting the green coffee beans; blending desired additives, such as perfumery, with the roasted coffee beans when desired; and grinding or crushing the roasted blended coffee beans to manufacture roasted ground or crushed coffee beans which are put on the market. To take coffee as a beverage, the roasted ground or crushed coffee beans are infused in hot steam of boiled water.
In the above-mentioned method for producing coffee, the roasting of the green coffee beans which is the initial process of the method means that the green coffee beans are heated and roasted until the color of the coffee beans changes from light chocolate brown into dark brown-black. Further, the roasting grades of the coffee beans may be classified into several grades from light roasting to dark roasting according to the extent of the roasting executed after the coffee beans are dewatered during the roasting process.
The roasted coffee beans have a flavor, such as a sour flavor, a bitter flavor or a sweet flavor. However, the green coffee beans do not have any flavor expected from the roasted coffee beans, but have only the smell of greens.
Thus, the roasting of the coffee beans means a process in which the green coffee beans are heated to cause a chemical change therein, resulting in generation of ingredients causing the flavor in the coffee beans. In other words, the roasting of the coffee beans causes the coffee beans to exhibit their properties and thereby enhance their taste and aroma. Therefore, the roasting of the coffee beans has become recognized as the most important process in the method for processing the coffee beans.
Conventional methods for roasting green coffee beans include a hot-air method, a half-hot-air method and a direct-fired method.
In the hot-air method, a burner chamber is provided to directly blow hot air at a controlled temperature into a rotary drum, thus using the hot air to roast green coffee beans contained in the rotary drum. In the half-hot-air method, hot air from a burner chamber is guided to a part of a rotary drum through a hot air guide pipe, thus indirectly roasting green coffee beans contained in the rotary drum while preventing the coffee beans from being directly affected by the flame of the burner chamber. In the direct-fired method, green coffee beans are contained in a rotary drum with a net structure, while the flame from a burner placed under the rotary drum reaches the rotary drum to directly roast the coffee beans.
However, the conventional coffee bean roasting methods which are executed using hot air or direct fire inevitably generate combustion gases from the burning of the coffee bean skins to cause bad coffee smells. Thus, the conventional coffee bean roasting methods must need smokestacks that are installed around coffee bean roasters to discharge the combustion gases from the roasters to the atmosphere. However, the smokestacks increase the space taken up by the coffee bean roasters. If the coffee bean roasters operate without the smokestacks, the combustion gases generated from the roasting of the coffee beans soak into the coffee beans, reducing the taste and aroma of the coffee.